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Plant Cell. 2014 Jul;26(7):2996-3009. doi: 10.1105/tpc.114.126862. Epub 2014 Jul 10.

The structure of the catalytic domain of a plant cellulose synthase and its assembly into dimers.

Author information

1
Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907-2054.
2
Department of Bioengineering, Northeastern University, Boston, Massachusetts 02115 Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115.
3
Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-1971.
4
National Renewable Energy Laboratory, Biomolecular Science Group, Golden, Colorado 80401-3305.
5
DeltaG Technologies, San Diego, California 92122.
6
Bindley Bioscience Center, Purdue University, West Lafayette, Indiana 47907-2057.
7
Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-1971 Department of Computer Science, Purdue University, West Lafayette, Indiana 47907-2107.
8
Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907-2054 Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-1971 Bindley Bioscience Center, Purdue University, West Lafayette, Indiana 47907-2057 carpita@purdue.edu.

Abstract

Cellulose microfibrils are para-crystalline arrays of several dozen linear (1→4)-β-d-glucan chains synthesized at the surface of the cell membrane by large, multimeric complexes of synthase proteins. Recombinant catalytic domains of rice (Oryza sativa) CesA8 cellulose synthase form dimers reversibly as the fundamental scaffold units of architecture in the synthase complex. Specificity of binding to UDP and UDP-Glc indicates a properly folded protein, and binding kinetics indicate that each monomer independently synthesizes single glucan chains of cellulose, i.e., two chains per dimer pair. In contrast to structure modeling predictions, solution x-ray scattering studies demonstrate that the monomer is a two-domain, elongated structure, with the smaller domain coupling two monomers into a dimer. The catalytic core of the monomer is accommodated only near its center, with the plant-specific sequences occupying the small domain and an extension distal to the catalytic domain. This configuration is in stark contrast to the domain organization obtained in predicted structures of plant CesA. The arrangement of the catalytic domain within the CesA monomer and dimer provides a foundation for constructing structural models of the synthase complex and defining the relationship between the rosette structure and the cellulose microfibrils they synthesize.

PMID:
25012190
PMCID:
PMC4145127
DOI:
10.1105/tpc.114.126862
[Indexed for MEDLINE]
Free PMC Article
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